Discovered a very cool technique for taking pictures of eyes, thanks to AndWhyNot . It involves using a remote controlled light shone through the eye piece to get the eye dead centre. I didn't have a remote controlled light handy, but I was able to use the light-up auto focus point selection function instead which worked really well. It's also a very useful feature for composing shots in the dark.
For this shot I worked out the minimum focusing distance of my lens and cut a piece of bamboo cane to the same length so I could measure the distance from the lens to my eye. I then centred my eye using the red auto focus selection dot and opened the shutter, at the same time setting of the flash (LumaPro LP160 set to 1/64 power, 105mm) via wireless trigger. I then put the lens cap on, zoomed out to from 22mm to 10mm, set focus to infinity, removed the lens cap and pointed the camera at the digital light wand while rotating the camera on my DIY "Twizzle-pod".
The green tinge is from in-camera custom white balance. This is straight from the camera, as shot, no photoshopping or adjustments.
I could probably get it a bit neater, but I've had enough of zapping myself in the eye for one night!